src/gpu/GrResourceCache.cpp - platform/external/skia - Gitiles


 /*
  * Copyright 2010 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */


 #include "GrResourceCache.h"
 #include "GrResource.h"

 DECLARE_SKMESSAGEBUS_MESSAGE(GrResourceInvalidatedMessage);

 GrResourceKey::ResourceType GrResourceKey::GenerateResourceType() {
     static int32_t gNextType = 0;

     int32_t type = sk_atomic_inc(&gNextType);
     if (type >= (1 << 8 * sizeof(ResourceType))) {
         GrCrash("Too many Resource Types");
     }

     return static_cast<ResourceType>(type);
 }

 ///////////////////////////////////////////////////////////////////////////////

 GrResourceEntry::GrResourceEntry(const GrResourceKey& key, GrResource* resource)
         : fKey(key), fResource(resource) {
     // we assume ownership of the resource, and will unref it when we die
     SkASSERT(resource);
     resource->ref();
 }

 GrResourceEntry::~GrResourceEntry() {
     fResource->setCacheEntry(NULL);
     fResource->unref();
 }

 #ifdef SK_DEBUG
 void GrResourceEntry::validate() const {
     SkASSERT(fResource);
     SkASSERT(fResource->getCacheEntry() == this);
     fResource->validate();
 }
 #endif

 ///////////////////////////////////////////////////////////////////////////////

 GrResourceCache::GrResourceCache(int maxCount, size_t maxBytes) :
         fMaxCount(maxCount),
         fMaxBytes(maxBytes) {
 #if GR_CACHE_STATS
     fHighWaterEntryCount          = 0;
     fHighWaterEntryBytes          = 0;
     fHighWaterClientDetachedCount = 0;
     fHighWaterClientDetachedBytes = 0;
 #endif

     fEntryCount                   = 0;
     fEntryBytes                   = 0;
     fClientDetachedCount          = 0;
     fClientDetachedBytes          = 0;

     fPurging                      = false;

     fOverbudgetCB                 = NULL;
     fOverbudgetData               = NULL;
 }

 GrResourceCache::~GrResourceCache() {
     GrAutoResourceCacheValidate atcv(this);

     EntryList::Iter iter;

     // Unlike the removeAll, here we really remove everything, including locked resources.
     while (GrResourceEntry* entry = fList.head()) {
         GrAutoResourceCacheValidate atcv(this);

         // remove from our cache
         fCache.remove(entry->fKey, entry);

         // remove from our llist
         this->internalDetach(entry);

         delete entry;
     }
 }

 void GrResourceCache::getLimits(int* maxResources, size_t* maxResourceBytes) const{
     if (NULL != maxResources) {
         *maxResources = fMaxCount;
     }
     if (NULL != maxResourceBytes) {
         *maxResourceBytes = fMaxBytes;
     }
 }

 void GrResourceCache::setLimits(int maxResources, size_t maxResourceBytes) {
     bool smaller = (maxResources < fMaxCount) || (maxResourceBytes < fMaxBytes);

     fMaxCount = maxResources;
     fMaxBytes = maxResourceBytes;

     if (smaller) {
         this->purgeAsNeeded();
     }
 }

 void GrResourceCache::internalDetach(GrResourceEntry* entry,
                                      BudgetBehaviors behavior) {
     fList.remove(entry);

     // update our stats
     if (kIgnore_BudgetBehavior == behavior) {
         fClientDetachedCount += 1;
         fClientDetachedBytes += entry->resource()->sizeInBytes();

 #if GR_CACHE_STATS
         if (fHighWaterClientDetachedCount < fClientDetachedCount) {
             fHighWaterClientDetachedCount = fClientDetachedCount;
         }
         if (fHighWaterClientDetachedBytes < fClientDetachedBytes) {
             fHighWaterClientDetachedBytes = fClientDetachedBytes;
         }
 #endif

     } else {
         SkASSERT(kAccountFor_BudgetBehavior == behavior);

         fEntryCount -= 1;
         fEntryBytes -= entry->resource()->sizeInBytes();
     }
 }

 void GrResourceCache::attachToHead(GrResourceEntry* entry,
                                    BudgetBehaviors behavior) {
     fList.addToHead(entry);

     // update our stats
     if (kIgnore_BudgetBehavior == behavior) {
         fClientDetachedCount -= 1;
         fClientDetachedBytes -= entry->resource()->sizeInBytes();
     } else {
         SkASSERT(kAccountFor_BudgetBehavior == behavior);

         fEntryCount += 1;
         fEntryBytes += entry->resource()->sizeInBytes();

 #if GR_CACHE_STATS
         if (fHighWaterEntryCount < fEntryCount) {
             fHighWaterEntryCount = fEntryCount;
         }
         if (fHighWaterEntryBytes < fEntryBytes) {
             fHighWaterEntryBytes = fEntryBytes;
         }
 #endif
     }
 }

 // This functor just searches for an entry with only a single ref (from
 // the texture cache itself). Presumably in this situation no one else
 // is relying on the texture.
 class GrTFindUnreffedFunctor {
 public:
     bool operator()(const GrResourceEntry* entry) const {
         return entry->resource()->unique();
     }
 };

 GrResource* GrResourceCache::find(const GrResourceKey& key, uint32_t ownershipFlags) {
     GrAutoResourceCacheValidate atcv(this);

     GrResourceEntry* entry = NULL;

     if (ownershipFlags & kNoOtherOwners_OwnershipFlag) {
         GrTFindUnreffedFunctor functor;

         entry = fCache.find<GrTFindUnreffedFunctor>(key, functor);
     } else {
         entry = fCache.find(key);
     }

     if (NULL == entry) {
         return NULL;
     }

     if (ownershipFlags & kHide_OwnershipFlag) {
         this->makeExclusive(entry);
     } else {
         // Make this resource MRU
         this->internalDetach(entry);
         this->attachToHead(entry);
     }

     return entry->fResource;
 }

 void GrResourceCache::addResource(const GrResourceKey& key,
                                   GrResource* resource,
                                   uint32_t ownershipFlags) {
     SkASSERT(NULL == resource->getCacheEntry());
     // we don't expect to create new resources during a purge. In theory
     // this could cause purgeAsNeeded() into an infinite loop (e.g.
     // each resource destroyed creates and locks 2 resources and
     // unlocks 1 thereby causing a new purge).
     SkASSERT(!fPurging);
     GrAutoResourceCacheValidate atcv(this);

     GrResourceEntry* entry = SkNEW_ARGS(GrResourceEntry, (key, resource));
     resource->setCacheEntry(entry);

     this->attachToHead(entry);
     fCache.insert(key, entry);

     if (ownershipFlags & kHide_OwnershipFlag) {
         this->makeExclusive(entry);
     }

 }

 void GrResourceCache::makeExclusive(GrResourceEntry* entry) {
     GrAutoResourceCacheValidate atcv(this);

     // When scratch textures are detached (to hide them from future finds) they
     // still count against the resource budget
     this->internalDetach(entry, kIgnore_BudgetBehavior);
     fCache.remove(entry->key(), entry);

 #ifdef SK_DEBUG
     fExclusiveList.addToHead(entry);
 #endif
 }

 void GrResourceCache::removeInvalidResource(GrResourceEntry* entry) {
     // If the resource went invalid while it was detached then purge it
     // This can happen when a 3D context was lost,
     // the client called GrContext::contextDestroyed() to notify Gr,
     // and then later an SkGpuDevice's destructor releases its backing
     // texture (which was invalidated at contextDestroyed time).
     fClientDetachedCount -= 1;
     fEntryCount -= 1;
     size_t size = entry->resource()->sizeInBytes();
     fClientDetachedBytes -= size;
     fEntryBytes -= size;
 }

 void GrResourceCache::makeNonExclusive(GrResourceEntry* entry) {
     GrAutoResourceCacheValidate atcv(this);

 #ifdef SK_DEBUG
     fExclusiveList.remove(entry);
 #endif

     if (entry->resource()->isValid()) {
         // Since scratch textures still count against the cache budget even
         // when they have been removed from the cache, re-adding them doesn't
         // alter the budget information.
         attachToHead(entry, kIgnore_BudgetBehavior);
         fCache.insert(entry->key(), entry);
     } else {
         this->removeInvalidResource(entry);
     }
 }

 /**
  * Destroying a resource may potentially trigger the unlock of additional
  * resources which in turn will trigger a nested purge. We block the nested
  * purge using the fPurging variable. However, the initial purge will keep
  * looping until either all resources in the cache are unlocked or we've met
  * the budget. There is an assertion in createAndLock to check against a
  * resource's destructor inserting new resources into the cache. If these
  * new resources were unlocked before purgeAsNeeded completed it could
  * potentially make purgeAsNeeded loop infinitely.
  *
  * extraCount and extraBytes are added to the current resource totals to account
  * for incoming resources (e.g., GrContext is about to add 10MB split between
  * 10 textures).
  */
 void GrResourceCache::purgeAsNeeded(int extraCount, size_t extraBytes) {
     if (fPurging) {
         return;
     }

     fPurging = true;

     this->purgeInvalidated();

     this->internalPurge(extraCount, extraBytes);
     if (((fEntryCount+extraCount) > fMaxCount ||
         (fEntryBytes+extraBytes) > fMaxBytes) &&
         NULL != fOverbudgetCB) {
         // Despite the purge we're still over budget. See if Ganesh can
         // release some resources and purge again.
         if ((*fOverbudgetCB)(fOverbudgetData)) {
             this->internalPurge(extraCount, extraBytes);
         }
     }

     fPurging = false;
 }

 void GrResourceCache::purgeInvalidated() {
     SkTDArray<GrResourceInvalidatedMessage> invalidated;
     fInvalidationInbox.poll(&invalidated);

     for (int i = 0; i < invalidated.count(); i++) {
         // We're somewhat missing an opportunity here.  We could use the
         // default find functor that gives us back resources whether we own
         // them exclusively or not, and when they're not exclusively owned mark
         // them for purging later when they do become exclusively owned.
         //
         // This is complicated and confusing.  May try this in the future.  For
         // now, these resources are just LRU'd as if we never got the message.
         while (GrResourceEntry* entry = fCache.find(invalidated[i].key, GrTFindUnreffedFunctor())) {
             this->deleteResource(entry);
         }
     }
 }

 void GrResourceCache::deleteResource(GrResourceEntry* entry) {
     SkASSERT(1 == entry->fResource->getRefCnt());

     // remove from our cache
     fCache.remove(entry->key(), entry);

     // remove from our llist
     this->internalDetach(entry);
     delete entry;
 }

 void GrResourceCache::internalPurge(int extraCount, size_t extraBytes) {
     SkASSERT(fPurging);

     bool withinBudget = false;
     bool changed = false;

     // The purging process is repeated several times since one pass
     // may free up other resources
     do {
         EntryList::Iter iter;

         changed = false;

         // Note: the following code relies on the fact that the
         // doubly linked list doesn't invalidate its data/pointers
         // outside of the specific area where a deletion occurs (e.g.,
         // in internalDetach)
         GrResourceEntry* entry = iter.init(fList, EntryList::Iter::kTail_IterStart);

         while (NULL != entry) {
             GrAutoResourceCacheValidate atcv(this);

             if ((fEntryCount+extraCount) <= fMaxCount &&
                 (fEntryBytes+extraBytes) <= fMaxBytes) {
                 withinBudget = true;
                 break;
             }

             GrResourceEntry* prev = iter.prev();
             if (entry->fResource->unique()) {
                 changed = true;
                 this->deleteResource(entry);
             }
             entry = prev;
         }
     } while (!withinBudget && changed);
 }

 void GrResourceCache::purgeAllUnlocked() {
     GrAutoResourceCacheValidate atcv(this);

     // we can have one GrResource holding a lock on another
     // so we don't want to just do a simple loop kicking each
     // entry out. Instead change the budget and purge.

     size_t savedMaxBytes = fMaxBytes;
     int savedMaxCount = fMaxCount;
     fMaxBytes = (size_t) -1;
     fMaxCount = 0;
     this->purgeAsNeeded();

 #ifdef SK_DEBUG
     SkASSERT(fExclusiveList.countEntries() == fClientDetachedCount);
     SkASSERT(countBytes(fExclusiveList) == fClientDetachedBytes);
     if (!fCache.count()) {
         // Items may have been detached from the cache (such as the backing
         // texture for an SkGpuDevice). The above purge would not have removed
         // them.
         SkASSERT(fEntryCount == fClientDetachedCount);
         SkASSERT(fEntryBytes == fClientDetachedBytes);
         SkASSERT(fList.isEmpty());
     }
 #endif

     fMaxBytes = savedMaxBytes;
     fMaxCount = savedMaxCount;
 }

 ///////////////////////////////////////////////////////////////////////////////

 #ifdef SK_DEBUG
 size_t GrResourceCache::countBytes(const EntryList& list) {
     size_t bytes = 0;

     EntryList::Iter iter;

     const GrResourceEntry* entry = iter.init(const_cast<EntryList&>(list),
                                              EntryList::Iter::kTail_IterStart);

     for ( ; NULL != entry; entry = iter.prev()) {
         bytes += entry->resource()->sizeInBytes();
     }
     return bytes;
 }

 static bool both_zero_or_nonzero(int count, size_t bytes) {
     return (count == 0 && bytes == 0) || (count > 0 && bytes > 0);
 }

 void GrResourceCache::validate() const {
     fList.validate();
     fExclusiveList.validate();
     SkASSERT(both_zero_or_nonzero(fEntryCount, fEntryBytes));
     SkASSERT(both_zero_or_nonzero(fClientDetachedCount, fClientDetachedBytes));
     SkASSERT(fClientDetachedBytes <= fEntryBytes);
     SkASSERT(fClientDetachedCount <= fEntryCount);
     SkASSERT((fEntryCount - fClientDetachedCount) == fCache.count());

     EntryList::Iter iter;

     // check that the exclusively held entries are okay
     const GrResourceEntry* entry = iter.init(const_cast<EntryList&>(fExclusiveList),
                                              EntryList::Iter::kHead_IterStart);

     for ( ; NULL != entry; entry = iter.next()) {
         entry->validate();
     }

     // check that the shareable entries are okay
     entry = iter.init(const_cast<EntryList&>(fList), EntryList::Iter::kHead_IterStart);

     int count = 0;
     for ( ; NULL != entry; entry = iter.next()) {
         entry->validate();
         SkASSERT(fCache.find(entry->key()));
         count += 1;
     }
     SkASSERT(count == fEntryCount - fClientDetachedCount);

     size_t bytes = countBytes(fList);
     SkASSERT(bytes == fEntryBytes  - fClientDetachedBytes);

     bytes = countBytes(fExclusiveList);
     SkASSERT(bytes == fClientDetachedBytes);

     SkASSERT(fList.countEntries() == fEntryCount - fClientDetachedCount);

     SkASSERT(fExclusiveList.countEntries() == fClientDetachedCount);
 }
 #endif // SK_DEBUG

 #if GR_CACHE_STATS

 void GrResourceCache::printStats() {
     int locked = 0;

     EntryList::Iter iter;

     GrResourceEntry* entry = iter.init(fList, EntryList::Iter::kTail_IterStart);

     for ( ; NULL != entry; entry = iter.prev()) {
         if (entry->fResource->getRefCnt() > 1) {
             ++locked;
         }
     }

     SkDebugf("Budget: %d items %d bytes\n", fMaxCount, fMaxBytes);
     SkDebugf("\t\tEntry Count: current %d (%d locked) high %d\n",
                 fEntryCount, locked, fHighWaterEntryCount);
     SkDebugf("\t\tEntry Bytes: current %d high %d\n",
                 fEntryBytes, fHighWaterEntryBytes);
     SkDebugf("\t\tDetached Entry Count: current %d high %d\n",
                 fClientDetachedCount, fHighWaterClientDetachedCount);
     SkDebugf("\t\tDetached Bytes: current %d high %d\n",
                 fClientDetachedBytes, fHighWaterClientDetachedBytes);
 }

 #endif

 ///////////////////////////////////////////////////////////////////////////////

	/*
	* Copyright 2010 Google Inc.
	*
	* Use of this source code is governed by a BSD-style license that can be
	* found in the LICENSE file.
	*/



	#include "GrResourceCache.h"
	#include "GrResource.h"

	DECLARE_SKMESSAGEBUS_MESSAGE(GrResourceInvalidatedMessage);

	GrResourceKey::ResourceType GrResourceKey::GenerateResourceType() {
	static int32_t gNextType = 0;

	int32_t type = sk_atomic_inc(&gNextType);
	if (type >= (1 << 8 * sizeof(ResourceType))) {
	GrCrash("Too many Resource Types");
	}

	return static_cast<ResourceType>(type);
	}

	///////////////////////////////////////////////////////////////////////////////

	GrResourceEntry::GrResourceEntry(const GrResourceKey& key, GrResource* resource)
	: fKey(key), fResource(resource) {
	// we assume ownership of the resource, and will unref it when we die
	SkASSERT(resource);
	resource->ref();
	}

	GrResourceEntry::~GrResourceEntry() {
	fResource->setCacheEntry(NULL);
	fResource->unref();
	}

	#ifdef SK_DEBUG
	void GrResourceEntry::validate() const {
	SkASSERT(fResource);
	SkASSERT(fResource->getCacheEntry() == this);
	fResource->validate();
	}
	#endif

	///////////////////////////////////////////////////////////////////////////////

	GrResourceCache::GrResourceCache(int maxCount, size_t maxBytes) :
	fMaxCount(maxCount),
	fMaxBytes(maxBytes) {
	#if GR_CACHE_STATS
	fHighWaterEntryCount = 0;
	fHighWaterEntryBytes = 0;
	fHighWaterClientDetachedCount = 0;
	fHighWaterClientDetachedBytes = 0;
	#endif

	fEntryCount = 0;
	fEntryBytes = 0;
	fClientDetachedCount = 0;
	fClientDetachedBytes = 0;

	fPurging = false;

	fOverbudgetCB = NULL;
	fOverbudgetData = NULL;
	}

	GrResourceCache::~GrResourceCache() {
	GrAutoResourceCacheValidate atcv(this);

	EntryList::Iter iter;

	// Unlike the removeAll, here we really remove everything, including locked resources.
	while (GrResourceEntry* entry = fList.head()) {
	GrAutoResourceCacheValidate atcv(this);

	// remove from our cache
	fCache.remove(entry->fKey, entry);

	// remove from our llist
	this->internalDetach(entry);

	delete entry;
	}
	}

	void GrResourceCache::getLimits(int* maxResources, size_t* maxResourceBytes) const{
	if (NULL != maxResources) {
	*maxResources = fMaxCount;
	}
	if (NULL != maxResourceBytes) {
	*maxResourceBytes = fMaxBytes;
	}
	}

	void GrResourceCache::setLimits(int maxResources, size_t maxResourceBytes) {
	bool smaller = (maxResources < fMaxCount) \|\| (maxResourceBytes < fMaxBytes);

	fMaxCount = maxResources;
	fMaxBytes = maxResourceBytes;

	if (smaller) {
	this->purgeAsNeeded();
	}
	}

	void GrResourceCache::internalDetach(GrResourceEntry* entry,
	BudgetBehaviors behavior) {
	fList.remove(entry);

	// update our stats
	if (kIgnore_BudgetBehavior == behavior) {
	fClientDetachedCount += 1;
	fClientDetachedBytes += entry->resource()->sizeInBytes();

	#if GR_CACHE_STATS
	if (fHighWaterClientDetachedCount < fClientDetachedCount) {
	fHighWaterClientDetachedCount = fClientDetachedCount;
	}
	if (fHighWaterClientDetachedBytes < fClientDetachedBytes) {
	fHighWaterClientDetachedBytes = fClientDetachedBytes;
	}
	#endif

	} else {
	SkASSERT(kAccountFor_BudgetBehavior == behavior);

	fEntryCount -= 1;
	fEntryBytes -= entry->resource()->sizeInBytes();
	}
	}

	void GrResourceCache::attachToHead(GrResourceEntry* entry,
	BudgetBehaviors behavior) {
	fList.addToHead(entry);

	// update our stats
	if (kIgnore_BudgetBehavior == behavior) {
	fClientDetachedCount -= 1;
	fClientDetachedBytes -= entry->resource()->sizeInBytes();
	} else {
	SkASSERT(kAccountFor_BudgetBehavior == behavior);

	fEntryCount += 1;
	fEntryBytes += entry->resource()->sizeInBytes();

	#if GR_CACHE_STATS
	if (fHighWaterEntryCount < fEntryCount) {
	fHighWaterEntryCount = fEntryCount;
	}
	if (fHighWaterEntryBytes < fEntryBytes) {
	fHighWaterEntryBytes = fEntryBytes;
	}
	#endif
	}
	}

	// This functor just searches for an entry with only a single ref (from
	// the texture cache itself). Presumably in this situation no one else
	// is relying on the texture.
	class GrTFindUnreffedFunctor {
	public:
	bool operator()(const GrResourceEntry* entry) const {
	return entry->resource()->unique();
	}
	};

	GrResource* GrResourceCache::find(const GrResourceKey& key, uint32_t ownershipFlags) {
	GrAutoResourceCacheValidate atcv(this);

	GrResourceEntry* entry = NULL;

	if (ownershipFlags & kNoOtherOwners_OwnershipFlag) {
	GrTFindUnreffedFunctor functor;

	entry = fCache.find<GrTFindUnreffedFunctor>(key, functor);
	} else {
	entry = fCache.find(key);
	}

	if (NULL == entry) {
	return NULL;
	}

	if (ownershipFlags & kHide_OwnershipFlag) {
	this->makeExclusive(entry);
	} else {
	// Make this resource MRU
	this->internalDetach(entry);
	this->attachToHead(entry);
	}

	return entry->fResource;
	}

	void GrResourceCache::addResource(const GrResourceKey& key,
	GrResource* resource,
	uint32_t ownershipFlags) {
	SkASSERT(NULL == resource->getCacheEntry());
	// we don't expect to create new resources during a purge. In theory
	// this could cause purgeAsNeeded() into an infinite loop (e.g.
	// each resource destroyed creates and locks 2 resources and
	// unlocks 1 thereby causing a new purge).
	SkASSERT(!fPurging);
	GrAutoResourceCacheValidate atcv(this);

	GrResourceEntry* entry = SkNEW_ARGS(GrResourceEntry, (key, resource));
	resource->setCacheEntry(entry);

	this->attachToHead(entry);
	fCache.insert(key, entry);

	if (ownershipFlags & kHide_OwnershipFlag) {
	this->makeExclusive(entry);
	}

	}

	void GrResourceCache::makeExclusive(GrResourceEntry* entry) {
	GrAutoResourceCacheValidate atcv(this);

	// When scratch textures are detached (to hide them from future finds) they
	// still count against the resource budget
	this->internalDetach(entry, kIgnore_BudgetBehavior);
	fCache.remove(entry->key(), entry);

	#ifdef SK_DEBUG
	fExclusiveList.addToHead(entry);
	#endif
	}

	void GrResourceCache::removeInvalidResource(GrResourceEntry* entry) {
	// If the resource went invalid while it was detached then purge it
	// This can happen when a 3D context was lost,
	// the client called GrContext::contextDestroyed() to notify Gr,
	// and then later an SkGpuDevice's destructor releases its backing
	// texture (which was invalidated at contextDestroyed time).
	fClientDetachedCount -= 1;
	fEntryCount -= 1;
	size_t size = entry->resource()->sizeInBytes();
	fClientDetachedBytes -= size;
	fEntryBytes -= size;
	}

	void GrResourceCache::makeNonExclusive(GrResourceEntry* entry) {
	GrAutoResourceCacheValidate atcv(this);

	#ifdef SK_DEBUG
	fExclusiveList.remove(entry);
	#endif

	if (entry->resource()->isValid()) {
	// Since scratch textures still count against the cache budget even
	// when they have been removed from the cache, re-adding them doesn't
	// alter the budget information.
	attachToHead(entry, kIgnore_BudgetBehavior);
	fCache.insert(entry->key(), entry);
	} else {
	this->removeInvalidResource(entry);
	}
	}

	/**
	* Destroying a resource may potentially trigger the unlock of additional
	* resources which in turn will trigger a nested purge. We block the nested
	* purge using the fPurging variable. However, the initial purge will keep
	* looping until either all resources in the cache are unlocked or we've met
	* the budget. There is an assertion in createAndLock to check against a
	* resource's destructor inserting new resources into the cache. If these
	* new resources were unlocked before purgeAsNeeded completed it could
	* potentially make purgeAsNeeded loop infinitely.
	*
	* extraCount and extraBytes are added to the current resource totals to account
	* for incoming resources (e.g., GrContext is about to add 10MB split between
	* 10 textures).
	*/
	void GrResourceCache::purgeAsNeeded(int extraCount, size_t extraBytes) {
	if (fPurging) {
	return;
	}

	fPurging = true;

	this->purgeInvalidated();

	this->internalPurge(extraCount, extraBytes);
	if (((fEntryCount+extraCount) > fMaxCount \|\|
	(fEntryBytes+extraBytes) > fMaxBytes) &&
	NULL != fOverbudgetCB) {
	// Despite the purge we're still over budget. See if Ganesh can
	// release some resources and purge again.
	if ((*fOverbudgetCB)(fOverbudgetData)) {
	this->internalPurge(extraCount, extraBytes);
	}
	}

	fPurging = false;
	}

	void GrResourceCache::purgeInvalidated() {
	SkTDArray<GrResourceInvalidatedMessage> invalidated;
	fInvalidationInbox.poll(&invalidated);

	for (int i = 0; i < invalidated.count(); i++) {
	// We're somewhat missing an opportunity here. We could use the
	// default find functor that gives us back resources whether we own
	// them exclusively or not, and when they're not exclusively owned mark
	// them for purging later when they do become exclusively owned.
	//
	// This is complicated and confusing. May try this in the future. For
	// now, these resources are just LRU'd as if we never got the message.
	while (GrResourceEntry* entry = fCache.find(invalidated[i].key, GrTFindUnreffedFunctor())) {
	this->deleteResource(entry);
	}
	}
	}

	void GrResourceCache::deleteResource(GrResourceEntry* entry) {
	SkASSERT(1 == entry->fResource->getRefCnt());

	// remove from our cache
	fCache.remove(entry->key(), entry);

	// remove from our llist
	this->internalDetach(entry);
	delete entry;
	}

	void GrResourceCache::internalPurge(int extraCount, size_t extraBytes) {
	SkASSERT(fPurging);

	bool withinBudget = false;
	bool changed = false;

	// The purging process is repeated several times since one pass
	// may free up other resources
	do {
	EntryList::Iter iter;

	changed = false;

	// Note: the following code relies on the fact that the
	// doubly linked list doesn't invalidate its data/pointers
	// outside of the specific area where a deletion occurs (e.g.,
	// in internalDetach)
	GrResourceEntry* entry = iter.init(fList, EntryList::Iter::kTail_IterStart);

	while (NULL != entry) {
	GrAutoResourceCacheValidate atcv(this);

	if ((fEntryCount+extraCount) <= fMaxCount &&
	(fEntryBytes+extraBytes) <= fMaxBytes) {
	withinBudget = true;
	break;
	}

	GrResourceEntry* prev = iter.prev();
	if (entry->fResource->unique()) {
	changed = true;
	this->deleteResource(entry);
	}
	entry = prev;
	}
	} while (!withinBudget && changed);
	}

	void GrResourceCache::purgeAllUnlocked() {
	GrAutoResourceCacheValidate atcv(this);

	// we can have one GrResource holding a lock on another
	// so we don't want to just do a simple loop kicking each
	// entry out. Instead change the budget and purge.

	size_t savedMaxBytes = fMaxBytes;
	int savedMaxCount = fMaxCount;
	fMaxBytes = (size_t) -1;
	fMaxCount = 0;
	this->purgeAsNeeded();

	#ifdef SK_DEBUG
	SkASSERT(fExclusiveList.countEntries() == fClientDetachedCount);
	SkASSERT(countBytes(fExclusiveList) == fClientDetachedBytes);
	if (!fCache.count()) {
	// Items may have been detached from the cache (such as the backing
	// texture for an SkGpuDevice). The above purge would not have removed
	// them.
	SkASSERT(fEntryCount == fClientDetachedCount);
	SkASSERT(fEntryBytes == fClientDetachedBytes);
	SkASSERT(fList.isEmpty());
	}
	#endif

	fMaxBytes = savedMaxBytes;
	fMaxCount = savedMaxCount;
	}

	///////////////////////////////////////////////////////////////////////////////

	#ifdef SK_DEBUG
	size_t GrResourceCache::countBytes(const EntryList& list) {
	size_t bytes = 0;

	EntryList::Iter iter;

	const GrResourceEntry* entry = iter.init(const_cast<EntryList&>(list),
	EntryList::Iter::kTail_IterStart);

	for ( ; NULL != entry; entry = iter.prev()) {
	bytes += entry->resource()->sizeInBytes();
	}
	return bytes;
	}

	static bool both_zero_or_nonzero(int count, size_t bytes) {
	return (count == 0 && bytes == 0) \|\| (count > 0 && bytes > 0);
	}

	void GrResourceCache::validate() const {
	fList.validate();
	fExclusiveList.validate();
	SkASSERT(both_zero_or_nonzero(fEntryCount, fEntryBytes));
	SkASSERT(both_zero_or_nonzero(fClientDetachedCount, fClientDetachedBytes));
	SkASSERT(fClientDetachedBytes <= fEntryBytes);
	SkASSERT(fClientDetachedCount <= fEntryCount);
	SkASSERT((fEntryCount - fClientDetachedCount) == fCache.count());

	EntryList::Iter iter;

	// check that the exclusively held entries are okay
	const GrResourceEntry* entry = iter.init(const_cast<EntryList&>(fExclusiveList),
	EntryList::Iter::kHead_IterStart);

	for ( ; NULL != entry; entry = iter.next()) {
	entry->validate();
	}

	// check that the shareable entries are okay
	entry = iter.init(const_cast<EntryList&>(fList), EntryList::Iter::kHead_IterStart);

	int count = 0;
	for ( ; NULL != entry; entry = iter.next()) {
	entry->validate();
	SkASSERT(fCache.find(entry->key()));
	count += 1;
	}
	SkASSERT(count == fEntryCount - fClientDetachedCount);

	size_t bytes = countBytes(fList);
	SkASSERT(bytes == fEntryBytes - fClientDetachedBytes);

	bytes = countBytes(fExclusiveList);
	SkASSERT(bytes == fClientDetachedBytes);

	SkASSERT(fList.countEntries() == fEntryCount - fClientDetachedCount);

	SkASSERT(fExclusiveList.countEntries() == fClientDetachedCount);
	}
	#endif // SK_DEBUG

	#if GR_CACHE_STATS

	void GrResourceCache::printStats() {
	int locked = 0;

	EntryList::Iter iter;

	GrResourceEntry* entry = iter.init(fList, EntryList::Iter::kTail_IterStart);

	for ( ; NULL != entry; entry = iter.prev()) {
	if (entry->fResource->getRefCnt() > 1) {
	++locked;
	}
	}

	SkDebugf("Budget: %d items %d bytes\n", fMaxCount, fMaxBytes);
	SkDebugf("\t\tEntry Count: current %d (%d locked) high %d\n",
	fEntryCount, locked, fHighWaterEntryCount);
	SkDebugf("\t\tEntry Bytes: current %d high %d\n",
	fEntryBytes, fHighWaterEntryBytes);
	SkDebugf("\t\tDetached Entry Count: current %d high %d\n",
	fClientDetachedCount, fHighWaterClientDetachedCount);
	SkDebugf("\t\tDetached Bytes: current %d high %d\n",
	fClientDetachedBytes, fHighWaterClientDetachedBytes);
	}

	#endif

	///////////////////////////////////////////////////////////////////////////////